I don't run that cam but I could believe it would run pretty poorly without a tune. It could be that the cam phasing is off but to check you're going to have to tear down the front of the engine again. I'd get the tune installed and see if that solves it. If not you'll have to break out the wrenches.

I know lots of people run that cam so they'll be able to help you with that question better than me....

 

I got the front tore down, just need to get the crank hub off

 

You're on the right track by tearing down the front of the engine first. It's obvious you did something drastically wrong in order to bend so many pushrods. Verifying everything you did is the way to go using process of elimination.

I'd first suspect that you installed the camshaft gear one tooth off which would advance or retard the valve timing (depending on which way it's off) a substantial amount causing piston to valve interference and power loss.

Keep us posted on what you find.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

 

I know some of the Crane rockers sold under the GMPP brand were lift limited to .550 or .575 depending who you ask. They had a shorter slot than the Crane branded version of the same rocker.

Granted you are not drasticly over lift BUT if the pushrods are off a little or you combine this with missadjustment I think you could bottom a lot of slots on the studs.

How did you find "zero lash"?

 

I was thinking it could be a tooth of causing valves to hit piston, but getting diffrent awnsers if this is posible

 

Spin push rod, tighten till hard to spin, 1/4 turn more.

I went back over them which was stupid and think I overtighten them.
Could this cause it.

Was the worst weekend to work on it. I was cold and wet, ran out of light and should have stopped till conditions better. Live and learn. Now taking time to go back over everything an fix problem/s, might be combination.

 

Spin the pushrod almost always results in way too tight.
All you have to do is turn the polylock down till it touches. move the pusrod vertically and you will see that it stops moving LONG LONG before you feel drag spinning it.

 

Yeah i think I tightened them to much, could this cause bent pushrods?

 

Most definitely. Did you set all of them on TDC without rotating the crank? That could cause it, but only 8 of them. Or if you just set themall without being at TDC whatsoever.

 

Most everyone has now abandoned the 'twist the pushrod' method since it so often leads to mis-adjusted lifters. Nowadays you'll see that, most often, the recommendation is to move the pushrod up and down when searching for ZERO lash. Once the pushrod can no longer be moved up or down, you've found ZERO lash.

Twisting was supposed to STOP when only slight resistance is felt, but this is where many have found their problem. What is 'SLIGHT" to one person isn't to another. some guys even continue to tighten until the pushrod can NO LONGER BE TWISTED, which is terribly wrong. So don't use and rely on the twisting method.

ALSO BE SURE THE LIFTER IS ON THE BASE CIRCLE OF THE CAM'S LOBE WHEN SEARCHING FOR ZERO LASH. The lifter can't be on the lobe's ramp or, worse still, the nose of the cam.

My experience is that if the lifter preload is set too tightly, what you'll find is one or more of the valves will be held open when it (they) should be closed. This usually results in a badly running engine, if it'll idle at all.

If only the exhausts are too tight you'll get back-firing in the exhaust or if only the intake valves you'll get back-firing in the intake.

With flat top pistons, I doubt if the piston(s) will hit the valves due to the preload being set too tightly. I doubt if the valve(s) would be held open high enough to cause that, but it's possible i guess.

Thinking on this more, If all 16 rods are bent, then we're looking for an area of mechanical binding. I'm considering rocker arn binding (possibly on the stud), pushrod binding against the cylinder head, valve spring coil bind, or the piston to valve clearance problems, in that order.

I believe if the cam gear was installed one tooth off, that would cause either the intake or the exhaust valves to come closer to the pistons, but not both. I haven't had to think about this in along time, so I have to research to find which move does what, but when the cam is advanced the piston to valve clearance of eight of the valves (either intakes or exhausts) decreases and if the camshaft is retarded, the opposite happens. I'll have to look it up to see which does what to be specific though.

There use to be a problem with stock (sled type) rocker arms binding against the studs causings rod problems. Also, on early iron L98 heads, the pushrod slots in the heads were too short and caused the rods to bind and bend when high ratio rockers were installed. Those are two areas worth investigating too.

The underside of the rockers to the valve spring retainers is another common area of interference.

Once you've checked and have verified that the cam was installed correctly it'll be time to check everything under the valve covers for proper clearance and any binding.

Hope this Helps.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

 

dupe

 

I sincerely doubt that the timing marks being off a tooth is going to cause piston contact with the valves and bend the pushrods...especially since he replaced them with a set of stock replacements and didn't have a repeat of the problem. Many people retard or advance their cams 5 degrees to modify the power band....a single tooth on the cam sprocket is about 10 degrees if I remember correctly. The cam being installed incorrectly will cause it to run poorly...I've seen it more than once....and that will be compounded by the lack of a tune.

By all means check the cam phasing...you can't go wrong by checking. However, that alone didn't cause bent pushrods. Too tight or too loose on the lifter preload is still the likely cause. And I'm still betting on too loose as to get them to bend on too tight you'd have to reach coil bind to 'stop' the rocker.

As Jake mentioned, we'll help get you the set up right under the valve covers....

 

Just pulled a valve cover and seen a rocker come of the valve had and setting on the edge, so I would say to loose.

 

take a look at the tips of the rocker arms, see if the two washers on each side of the roller tip are contacting the retainers on your springs. I bet they are.

 

Over the past couple of months, several guys have had problems with self-aligning rockers. they even posted photos of the damage caused and with a rocker sitting on the side of a valve spring. Also, I've recently seen a couple of photos where the self-aligning guides were actually riding on the spring retainer. Those are the main reasons I now recommend NON self aligning rocker arms when guys post asking which way to go.

I now recommend NSA rockers in spite of the responses I've read from posters saying "I've been running self-aligning rockers since the beginning of time with no problem", LOL It only takes "one time" and that "one time" seems to be popping up more and more lately.

We still need to know the exact procedure you followed when you set the lifter preload. Could be that something in how you did it will give us a clue.

Also, it would be helpful if you could post some photos of your valve train, close enough so we can see all the clearances we've mentioned so far.

I once calculated the amount of cam timing difference the movement of one gear tooth causes but I can't for the life of me remember the numbers. Chalk that up to 'old age' I guess.

Keep us posted and we'll solve this.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!